A polyphenylene ether has been extensively used because of superiority in its mechanical properties, electrical properties and heat resistance and further superiority in its dimensional stability. However, it is inferior in its molding processability when used singly. In order to improve the molding processability, JP-B-45-997 proposes a technique, wherein a polyamide is blended therewith. At present, such a material has come to be extensively used.
A technique of adding an impact improving material to a polymer alloy comprising a polyphenylene ether and a polyamide in order to impart impact resistance is disclosed in, for example, JP-A-2-11656.
JP-A-64-81852 and JP-A-2-58563 disclose a technique, wherein two kinds of elastomers, namely, an ABA type tri-block copolymer and an AB type di-block copolymer are blended with each other, to improve impact resistance. Further, JP-A-6-240130 discloses a technique, wherein more than one block copolymer having different weight ratios of an aromatic vinyl compound block are blended, thereby improving molding processability, mechanical properties and heat resistance.
In recent years, the needs from the market for the polyamide/polyphenylene ether alloy have been diversified and have reached a high level.
For example, a relay box material, which is one of the car electrical device parts, is installed in a high temperature environment in an engine room and, therefore, has been strongly demanded to maintain its impact strength even after heat exposure for a long period of time. In addition, under a trend toward a thinner relay box material for the production of a lightweight car, foreign matter (called a black spot and mainly composed of a raw material carbide), which is generated and incorporated at the time of its production, is apt to cause a problem such as short circuits. Therefore, the reduction of the foreign matter has been strongly demanded.
Further, within recent years, the extruder has been remarkably improved in its performance (i.e. megacompounder), so that the output at the time of extrusion can be far increased.
Since the polyamide/polyphenylene ether alloy is a polymer alloy accompanying a chemical reaction, however, its compatibility is altered by the increase of the output, to rapidly deteriorate the surface appearance after molding. As a result, there clearly appears a problem that the output in the extrusion of the polyamide/polyphenylene ether alloy cannot be sufficiently increased, and as a result, the productivity is decreased.
These problems, that have recently appeared, cannot be sufficiently solved by the above-mentioned conventional techniques, resulting in the problem that extensive applicability of the polyamide/polyphenylene ether alloy in various fields is hindered.
An object of the present invention is to solve these problems of the polyamide/polyphenylene ether alloy at the same time, namely the deterioration of surface appearance in a molded piece when extruded at a high output, deterioration in impact resistance after heat exposure and occurrence of foreign matter at the time of production.